The cosmetic products, such as foundations, blushers, eye shadows, lipsticks, etc., which are used for the makeup of skin and lips are largely comprised of inorganic powders and various organic powders.
By applying these products on the skin surface, a thin colored film is formed, which serves the function of masking the esthetic skin flaws and conferring a more even appearance.
It is known that direct contact of inorganic and organic cosmetic powders with the skin may lead to the absorption of the water on the skin surface, thus altering the natural hydrophilic and lipophilic balance, which may cause localized dehydration effects and consequently unpleasant feelings by those using these products.
Also, the lack of homogeneity of the powders used, having different physical features from one another, may ultimately generate clearly perceptible defects.
It is known the use of silicones in the field of cosmetic powders.
For example, U.S. Pat. No. 5,496,544 concerns a skin cosmetic composition consisting of an anhydrous powder comprising a solid powder phase mixed with a fat-based binder which contains a silicone mixture comprising at least one silicone oil, at least one silicone wax, at least one silicone resin, and optionally at least on silicone rubber and optionally at least one phenyl dimethicone.
However, in U.S. Pat. No. 5,496,544, the anhydrous powder undergoes a physical treatment by said fat-based binder. Therefore, in the cosmetic composition from U.S. Pat. No. 5,496,544, the absence of a covalent chemical bond between the powder phase and fat-based binder has the drawback of an easy extraction of the latter from the powder phase. Also, in the cosmetic composition from U.S. Pat. No. 5,496,544, the powder phase coating consists of complex mixtures of silicones which confer a different kind of sensorial effects on the skin itself.
EP 1 116 753 describes a powder treated with reactive silicone comprising a powder surface-coated with a silicone compound, in which the amount of hydrogen generated from Si—H groups left on the surface of the silicone-treated powder is not greater than 0.2 ml/g of the treated powder and a contact angle between the water and the treated powder is at least 100°.
However, the direct reaction between methylhydrogenpolysiloxane containing reactive Si—H bonds and the powder surface described in EP 1 116 753 never reaches completion and it has the disadvantage to release some H2 over time, which is the cause of several drawbacks for the obtained cosmetic powder. Indeed, on the one hand the generation of H2 may cause the containers carrying the powder to swell and deteriorate, on the other hand the powder itself may harden and break.
Moreover, the powder obtained by means of the direct reaction between methylhydrogenpolysiloxane containing reactive Si—H bonds and the powder surface itself, once subjected to pressing, exhibits a non-homogeneous and non-compact appearance due to development of H2 over time.
In fact it is known that a cosmetic powder should simultaneously have all the following properties:                being densely and homogeneously pressed with a drop strength of at least 10 cm,        being able to give good sensorial feeling features on skin (smoothness or flowingness during application),        ensuring an excellent skin adhesion so as to be able to last long (long lasting);        being spreadable and fadeable during application (ease of application)        being endowed with a good hydrophobicity, i.e. the powder feature of remaining dry in contact with water. Such a feature is commonly measured by determining the surface tension of solutions, with a known surface tension, deposited on the surface of the powder itself.        